windows下nginx配置后，http訪問pending怎么回事？

conf配置如下
security_ui 下是靜態(tài)頁面，訪問沒問題
http://safeguard 對(duì)應(yīng)的是后臺(tái)程序
譬如訪問 http://localhost:8090/api/index?msisdn=bc65670205bff064f878d61afa2e98b5&channel=null
訪問的時(shí)候時(shí)不時(shí)pending，有時(shí)很快，有時(shí)很久才得到響應(yīng)
怎么回事？
ps：不用8090端口進(jìn)行nginx路由，直接用8080就沒問題

upstream safeguard{
   server localhost:8080;
   #server 192.168.194.72:8013;
   #ip_hash;
}

server {
    listen       8090;
    server_name  localhost;

    #charset koi8-r;

    #access_log  logs/host.access.log  main;

    location / {
        root   html;
        proxy_pass http://safeguard;
        index  index.html index.htm;
    }


    location /security_ui {
        root   D:\svn\safeGuard;
        index  index.html index.htm;
    }
    。。。
    

nginx log日志：

2018/03/27 19:25:04 [error] 11868#9296: *192 upstream timed out (10060: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond) while connecting to upstream, client: 127.0.0.1, server: localhost, request: "GET /api/index/pIndex?msisdn=bc65670205bff064f878d61afa2e98b5&channel=null HTTP/1.1", upstream: "http://[::1]:8080/api/index/pIndex?msisdn=bc65670205bff064f878d61afa2e98b5&channel=null", host: "localhost:8090", referrer: "http://localhost:8090/security_ui/html/index.html?msisdn=bc65670205bff064f878d61afa2e98b5&channel=null"
2018/03/28 10:48:02 [error] 4092#212: *7 upstream timed out (10060: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond) while connecting to upstream, client: 127.0.0.1, server: localhost, request: "GET /api/index/pIndex?msisdn=bc65670205bff064f878d61afa2e98b5&channel=null HTTP/1.1", upstream: "http://[::1]:8080/api/index/pIndex?msisdn=bc65670205bff064f878d61afa2e98b5&channel=null", host: "localhost:8090", referrer: "http://localhost:8090/security_ui/html/index.html?msisdn=bc65670205bff064f878d61afa2e98b5&channel=null"